The present invention relates generally to brake systems for trains, and more specifically, to a brake system for trains having a mixture of electro-pneumatic (EP) brake valves and pneumatic brake valves on different cars.
In the U.S. and other countries which use the standard of the American Association of Railroads (“AAR”), railroads have been studying and implementing electro-pneumatic brake valves in the individual cars. Not all railroads are capable of or want a complete train with electro-pneumatic brake valves. Some railroads prefer to have a mixture of electro-pneumatic brake valve cars with pneumatic brake valve cars. In an electro-pneumatic train, the brake pipe is maintained at its full value and the electrical signals provided to the electro-pneumatic valves produce a pneumatic braking on the EP cars. Since the brake pipe is always at its full value or release, the pneumatic brake valve cars have to be controlled by an adjacent electro-pneumatic car. This will be accomplished by a separate brake signal pipe which connects the electro-pneumatic car to the adjacent pneumatic car. A problem arises if this brake signal pipe is disconnected, as is the brake pipe. One or both of the cars may not be able to automatically apply their brakes in response to a breakaway. This is especially critical to the last car on the train since it is not connected to any other car which may be capable of bringing that segment of the train to a stop.
One solution to the problem is providing a special electro-pneumatic last car which would be designed not to be connected to a brake signal pipe. For some railroads, the dedication of a special end car may not be convenient or desirable.
The present disclosure is directed to a train including a brake pipe and an electrical train line extending from at least one locomotive through at least first and second cars which are adjacent to each other and connected by a brake signal pipe. The first car includes a first brake cylinder, a first reservoir and an electro-pneumatic brake valve. The electro-pneumatic brake valve is responsive to electric signals on the train line to produce a first car pneumatic apply brake signal from the first reservoir and release brake signal for the first brake cylinder and the brake signal pipe. The first car also includes a first valve to transmit the first brake signals to the brake signal pipe and to isolate the connection to the brake signal pipe for a breakaway at one of the cars. The second car includes a second brake cylinder, a second reservoir, and a pneumatic brake control valve. The pneumatic brake control valve is responsive to the first car pneumatic brake signals on the brake signal pipe and brake pipe pressure in the brake pipe to produce a second car pneumatic apply and release brake signals for the second brake cylinder corresponding to the first apply and release brake signals. The pneumatic brake control valve also produces a second car pneumatic apply brake signal from the second reservoir for an emergency pressure in the brake pipe and no brake signal on the brake signal pipe.
This system allows both cars to apply their brakes for a brake-way condition no matter where they are in the train.
These and other aspects of the present method will become apparent from the following detailed description of the method, when considered in conjunction with accompanying drawings.